When an aircraft intends to land on a runway for which no instrument approach procedure exists, it may descend on the instrument approach to another runway and, provided the required visual references are established at the circling Minimum Descent Altitude/Height, manoeuvre visually for landing on the desired runway. This procedure is used when landing on the instrument runway is undesirable, due for example to wind conditions or work in progress.
A circling approach is an extension of an instrument approach procedure which provides for visual circling of the aerodrome prior to landing. (ICAO Doc 8168: Procedures for Air Navigation Services - Aircraft Operations (PANS-OPS) Vol I - Flight Procedures)
A circling approach is the visual phase of an instrument approach to bring an aircraft into position for landing on a runway which is not suitably located for a straight-in approach. (JAR-OPS 1.435 (a) (1))
Go-around from a Circling Approach
Because the runway on which the aircraft makes the instrument approach is not the runway to which it is circling, confusion may exist in a pilot's mind if a go-around should become necessary. This would create a dangerous situation if, for example, the pilot flew the missed approach for the landing runway instead of the instrument runway. Therefore a standard procedure has been established by ICAO to address this issue:
If visual reference is lost while circling to land from an instrument approach, the missed approach specified for that particular procedure shall be followed. The transition from the visual (circling) manoeuvre to the missed approach should be initiated by a climbing turn, within the circling area, towards the landing runway, to return to the circling altitude or higher, immediately followed by interception and execution of the missed approach procedure. The indicated airspeed during these manoeuvres shall not exceed the maximum indicated airspeed associated with visual manoeuvring. (ICAO Doc 8168: PANS-OPS, Volume 1, Chapter 7, Section 7.4)